Abrasive roll assemblies are commonly used in a milling machine such as vertical abrasive type milling machine, having a milling chamber for polishing or whitening food grains, in particular rice grains. In the vertical abrasive type milling machine, the food grains to be milled are freely supplied from a food grain feeding system to the vicinity of the screw conveyor, through which the food grains are supplied to the milling chamber. The food grains are milled in the milling chamber formed by abrasive roll assemblies and perforated arcute sheet cover assemblies. The abrasive roll assemblies are assembled with abrasive stones for milling or whitening food grains received from the screw conveyor. The abrasive roll assemblies are configured as food grain polisher for the milling machine and are driven by a main shaft to polish the food grains.
In the milling machine, each abrasive roll assembly are mounted on a vertical main shaft extending vertically one over the other, and are rotated with the help of main shaft during milling. The food grains hits the abrasive stones of the abrasive roll assemblies in the milling chamber and milling action takes place inside the milling chamber. The milled food grains collected at bottom of milling chamber discharged through discharge disk. One of the conventional vertical milling machines is provided with milling parts and the main shaft, which discloses that the main shaft is present through out the milling machine and is being connected to all the abrasive roll assemblies for its rotation to maintain integrity of the milling machine.
Normally, the last or bottom most abrasive roll assembly can easily and rapidly wears in comparison with other abrasive roll assemblies in the milling machine during use. The worn-out last abrasive roll assembly affects overall performance and efficiency of the milling machine, and therefore it has to be replaced after the specific time. Since the existing milling machines consist of the vertical main shaft on which all the abrasive roll assemblies are placed one over the other, the entire vertical shaft along with abrasive roll assemblies should be taken off during maintenance work, even for replacing the last abrasive roll assembly.
With respect to all the conventional milling machines, it is necessary to disassemble each abrasive roll assemblies of the milling machine in order to access and replace the worn-out abrasive roll assembly, since all the roll assemblies are directly coupled to the vertical main shaft throughout for its rotation. Further, the disassembling of milling machine is very time and labor consuming and too tedious, as the construction of rotor main shaft is complicated and the replacement of bottom worn-out abrasive roll requires dismantling of rotor shaft assembly and various other parts of the milling machine, which increases repair and maintenance time and disturbs pulley and axial alignment of the milling machine. For higher capacity milling machines, the volume of milling chamber is changed by increasing the diameter of the abrasive roll assemblies and screen assembly, thus increasing the weight of each components of the milling machine. Hence, it increases the difficulty of assembly and disassembly of each component, and also increases installation time and maintenance cost of the milling machine.
Therefore, it is desirable to provide an improved and unique abrasive roll assembly for a milling machine, which is capable of overcoming the aforementioned drawbacks. The present arrangement of abrasive roll assembly aids easy removal and replacing of the worn-out roll assembly without dismantling all components of the milling machine and without altering pulley and axial alignment.